Question: Ishaan did 20 more sit-ups than Vanessa at night. Ishaan did 27 sit-ups. How many sit-ups did Vanessa do?
Ishaan did 27 sit-ups, and Vanessa did 20 fewer than that, so find the difference. The difference is $27 - 20$ sit-ups. He did $27 - 20 = 7$ sit-ups.